The present invention relates to an apparatus for tissue treatment, such as for cosmetic tissue treatment, and more particularly to a handpiece for a tissue treatment apparatus comprising a light source.
It is known to utilise laser light for tissue treatment.
During tissue treatment, a laser ablates a thin epidermal layer of the derma of a patient. During healing, a new epidermal layer is formed on the ablated surface having the look of the derma of a young person, i.e. the new epidermal layer is formed without previously existing scars, wrinkles, etc.
Lasers that operate at a wavelength that is absorbed in water are used for tissue treatment. When the laser power density (W/mm2) at illuminated cells is sufficient, cellular water is superheated causing small explosions that disrupt heated cells.
During removal of an epidermal layer, it is essential not to damage underlying or surrounding tissue. Residual heat may cause non-ablated cells to char and become necrotic, whereby new scars may be formed and thus, it is desirable to apply laser power for a short time, to minimize transmission of conducted heat to underlying and surrounding tissue.
It is therefore desired to accurately control the amount of light energy transferred to derma to be ablated. The amount of energy must be sufficient for the dermal cells to vaporize and, simultaneously, the amount of residual energy heating non-ablated cells must be so low that non-ablated cells will not be damaged.
Apparatuses for tissue treatment are known, comprising a CO2 laser emitting a laser beam and a laser articulating arm with mirrors for reflection of the laser beam, so that the laser beam is transmitted inside the articulating arm. Further, the arm has a number of joints, so that the arm can be moved around by an operator. A handpiece to be held by the operator is connected to the arm. The laser beam is moved or scanned across a target surface by movable mirrors connected to motors and mounted in the arm. The scan pattern of the laser beam is an archimedes spiral. The laser spot formed by the laser beam on the target surface moves along the spiral at a constant angular speed.
It is a disadvantage of the known apparatus that the energy density delivered to the target surface is non-uniform across the scanned surface area of the spiral, as more energy is delivered at the centre of the spiral than at the circumferential of the spiral.
It is another disadvantage of the known apparatus that the circular outline of the scan pattern leads to non-uniform scanning of an area that is larger than the area of the scan spiral as either 1) areas that have not been scanned will remain on the surface, when abutting spirals or 2) ablated areas will be scanned more than once, due to overlap of spirals.
It is yet another disadvantage of the known apparatus that evaporated derma is exhausted through the internal of the laser articulation arm, whereby optics and other members in the arm get dirty.
It is still another disadvantage of the known apparatus that it is very laborious to disassemble members, that may have been in contact with a patient, from the handpiece, e.g., for autoclaving.
It is still another disadvantage of the known apparatus that movement of the handpiece is restrained by the laser articulation arm, as the construction of tubes interconnected by joints is not fully flexible.
In addition, these apparatus typically have large mass and a large inertia (typically also due to counter-balancing masses) which makes the operation and movement of the arm difficult and heavy.
Under the name Uni-laser 450P, Asah Medico A/S, Denmark, markets an apparatus for cosmetic tissue treatment, comprising a CO2 laser and an optical fiber coupled to the laser at one end and to a handpiece at the other end.
It is a disadvantage of this known apparatus that the laser beam is manually scanned across the target surface whereby the quality of the treatment is determined and limited by the skill of the operator.
It is an object of the present invention to provide an apparatus for tissue treatment that is adapted to automatically and accurately ablate dermal cells to a desired depth causing only a minimum of damage to cells that are not removed.
It is another object of the present invention to provide an apparatus for tissue treatment that is adapted to ablate dermal cells uniformly and from a large area of a patient.
It is a further object of the present invention to provide an apparatus for tissue treatment, having a handpiece that can be moved around, i.e. traversed and rotated, freely by an operator, i.e. without exerting forces acting against the movement.
According to a first aspect of the invention, the above-mentioned and other objects are fulfilled by a handpiece for tissue treatment, comprising an input connector for connection of a first beam-outlet end of a first optical fiber to the handpiece and for alignment of the first optical fiber with an axis of the handpiece so that a first light beam emitted from the first beam-outlet end is transmitted substantially along the axis. The handpiece further comprises movable first deflecting means for deflection of the first light beam emitted from the first beam-outlet end of the first optical fiber into a second light beam, and an output for emission of the second light beam towards a target surface.
According to a second aspect of the invention, an apparatus for tissue treatment is provided, comprising a handpiece as described above. The apparatus further comprises a light source for emission of a light beam and being connected to the handpiece with an optical fiber for transmission of the light beam to the handpiece.
When the handpiece is kept in a fixed position in relation to a target surface that is illuminated by the second light beam changing of the position of the deflecting means causes the second light beam to traverse or scan the target surface along a curve. An area may be traversed or scanned by the second light beam, e.g. by letting the second light beam traverse or scan a meander like curve substantially covering the area or, by traversing or scanning the area line by line. In the present context, the type, number and shape of curves traversed by the second light beam in order to traverse a specific area is denoted the traversing pattern or the scan pattern. The area that is scanned or traversed by the second light beam is denoted the scan area, the treatment area or the traversed area.
Cellular water absorbs light energy, and applying light energy to the cells is therefore an efficient way of ablating tissue. Thus, it is preferred to use light sources, such as lasers, generating light at wavelengths with a high absorption in water, preferably wavelengths larger than 190 nm, such as wavelengths in the range from 190 nm to 1900 nm, preferably from 700 nm to 900 nm, and even more preferred approximately 810 nm, or, preferably wavelengths larger than 1900 nm, such as wavelengths in the range from 1900 nm to 3000 nm, preferably from 1900 nm to 2200 nm, preferably from 1900 nm to 2100 nm, and even more preferred approximately 2100 nm, or, from 2800 nm to 3000 nm, and even more preferred approximately 2930 nm, or wavelengths equal to or greater than 4500 nm, such as wavelengths in the range from 4500 nm to 11000 nm, preferably from 4500 nm to 5500 nm, alternatively from 10000 nm to 11000 nm, such as around 10600 nm.
The apparatus according to the invention may not only be used for ablating a thin epidermal layer of the derma of a patient. Also marks on the tissue such as marks from chloasma, liver spots, red spots, tattoos, blood vessels just below the surface, etc., as well as warts, wounds, hair follicles, etc. may be ablated or treated, and hereafter the terms tissue and resurfacing will include these marks and treatments thereof.
It is preferred, that the light source utilized in the present invention is a laser, but also other light sources, such as light emitting diodes and halogen bulbs, may be utilized.
The laser may be any laser capable of emitting light with sufficient power for illuminated cells to vaporize, such as CO2 lasers, YAG lasers, such as Erbium YAG lasers, Holmium YAG lasers, Nd YAG lasers, etc., semi conductor lasers, pulsed lasers, gas lasers, solid state lasers, Hg lasers, excimer lasers, etc.
Present CO2 lasers emit light at a wavelength of 10600 nm. The CO2 laser is particularly well suited as a light source in an apparatus for ablating dermal cells as water has a high energy absorbance at 10600 nm and the CO2 laser is capable of reliably delivering the required laser power.
Erbium YAG lasers emit light at a wavelength of 2930 nm. Water absorbs less energy at this wavelength that at 10600 nm. Therefore, the Erbium YAG laser may be preferred for ablating thinner layers of dermal cells than may be ablated with a CO2 laser. Tissue having been treated with light emitted from an Erbium YAG laser may heal faster than tissue having been treated with CO2 laser light as a thinner layer of dermal cells is influenced by Erbium YAG laser light. An erbium YAG laser may also be preferred when photocoagulation of blood vessels should be avoided.
A CO laser emits light in the 4500 nm to 5500 nm wavelength range. Water absorption at these wavelengths is somewhat less than water absorption at 10600 nm. A CO laser light source is presently preferred for dental treatment, e.g. for removal of carries, as dentine is not influenced by illumination of light from a CO laser.
A Nd YAG laser with a frequency doubled output beam in the 520-680 nm wavelength range is presently preferred as a light source for treatment of hypervasculation. Light in this wavelength range causes photocoagulation of blood without affecting surrounding tissue provided that an appropriate intensity of the light beam is directed towards the micro vessels for an appropriate period of time. Coagulation stops blood flow in the treated vessels whereby discoloration of the skin also stops.
Typically, a power density greater than about 50 W/mm2, such as a power density in the range from about 50 W/mm2 to about 180 W/mm2, is adequate for vaporizing cells with a minimum of damage to the surrounding tissue.
However, when removing hairs, the wavelength of the light is preferred to be approx. 800 nm. At this wavelength the absorbtion of the light in the hair follicles is lower than at higher wavelengths, and the power density must therefore be higher than 180 W/mm2, preferable higher than 300 W/mm2. Generally, the power density is adapted to the wavelength and the tissue to be treated.
The optical fiber for interconnection of a light source with a handpiece according to the present invention may be any fiber, such as a poly-crystalline silver halide fiber, etc, that is suitable for transmission of light emitted from the light source and that is made of a material that allows repeated bending of the fiber, so that an operator can freely manipulate the handpiece in order to direct the light beam toward various areas of a patient.
It is preferred to shape the handpiece ergonomically so that a comfortable hand grip is provided for the operator of the apparatus. For example, it is preferred to direct the light beam towards a target area at a substantially right angle to the area. The ergonomic form of the handpiece allows the operator to point the light beam at a substantially right angle to the target surface without having to bend the wrist in an uncomfortable way.
Preferably, the handpiece is light so that it is easy for the operator to hold the handpiece and bring it into any desired position in relation to a target surface to be treated. The weight of a preferred handpiece according to the present inventionxe2x80x94cables and fibers not includedxe2x80x94is less than 300 grams, such as 290 grams, or such as 250 grams.
User interface means may be provided for selection of parameters relating to the operation of the handpiece, positioned on the housing of the handpiece.
The parameters may comprise traversing velocity of the output light beam from the handpiece, intensity of the output light beam emitted form the handpiece, size of the target surface area to be traversed by the output light beam, shape of the target surface area to be traversed by the output light beam, etc.
The user interface means may comprise a first button, e.g. a membrane switch, for selection of a parameter type by stepping through a set of parameter types, such as the set listed above or any subset thereof.
The user interface means may further comprise a second button, e.g. a membrane switch, for selection of a parameter value of the parameter type currently selected by stepping through a corresponding set of parameter values.
A set of light emitting diodes may be provided for indication of the set of currently selected parameter values.
It is an important advantage of provision of the user interface at the handpiece that an operator of the handpiece is able to simultaneously select operational parameters of the handpiece and observe resulting changes in treatment effects as the operator is not forced to shift his field of view from the surface area to be treated to a user interface panel positioned somewhere else, e.g. behind the operator.
Preferably, the buttons are positioned on the housing of the handpiece so that single-handed operation is possible, preferably, with the right as well as with the left hand.
The user interface means may further comprise a foot pedal. The output beam traverses a target surface area when the operator depresses the pedal. Preferably, output beam traversing is stopped immediately when the operator releases the pedal.
The deflecting means may comprise any optical component or components suitable for deflecting light of the wavelength in question, such as mirrors, prisms, grids, diffractive optical elements, such as holograms, etc, etc.
The deflecting means are preferably movably mounted for displacement of the deflecting means as a function of time, so that the light beam emitted from the handpiece may traverse a surface along a desired curve while the handpiece is kept in a fixed position. Preferably, the deflecting means are rotatably mounted, and the actual deflection of the light beam is determined by the current angular position of the deflecting means.
Moving means may be utilized to control positions of the deflecting means, such as actuators, such as piezo electric crystals, the displacement of which is controlled by applying a specific electric voltage to their electrodes, electro motors generating linear or rotational displacements, galvanometers, magnetically activated or controlled actuators, pneumatic actuators, hydraulic actuators, etc.
The positions of the deflecting means may be controlled by deflecting control means adapted to control the moving means so that the deflecting means deflect the light beam in such a way that it traverses a target surface along a desired curve.
According to a preferred embodiment of the invention, a handpiece is provided, having two mirrors that are rotatably mounted in the path of the light beam in the handpiece. The rotational axis of the mirrors may be substantially perpendicular to each other in order to obtain two dimensional deflection of the light beam.
Alternatively, the movable deflecting means may comprise one mirror that is rotatable around two axes that may be substantially perpendicular to each other.
The moving means for the mirrors may be constituted by electro motors, e.g. each mirror may be directly connected to a shaft of a corresponding motor, whereby each motor is used for angular positioning of the corresponding mirror.
In order to minimize the size of the handpiece, it is preferred to mount the motors with their respective shafts in a common plane. For example, one motor may be a linear motor, such as a linear step motor, generating linear displacements. The shaft of this motor may be connected to the mirror at a first edge of the mirror, while a second and opposite edge of the mirror is rotatably connected to the handpiece. By pushing or pulling the first edge by the linear motor, the mirror is rotated about its rotational axis. The other motor, preferably a galvanometer, may be connected to the other mirror in the conventional way described above, whereby the two mirrors may be rotated around substantially perpendicular axes.
The deflecting control means may be adapted to control the moving means so that the desired curve is a substantially straight line.
Preferably, the deflecting control means are adapted to control the moving means so that the light beam traverses a target surface area line by line.
It is an important advantage of the line by line traversing pattern that areas of any arbitrary shape, such as polygonal, such as rectangular, quadratic, triangular, etc, or circular, elliptic, etc, may be traversed line by line by appropriately controlling the starting point and stopping point of light emission along each line traversed.
Preferably, the first deflecting control means are adapted to control the first moving means so that the lines are traversed sequentially i.e. neighbouring lines are traversed successively. This minimizes the requirement for the operator to be able to keep the handpiece steady in a desired position because when lines are traversed successively, neighbouring lines are traversed within a very short time period so that involuntary hand movements of the operator does not lead to traversing overlap i.e. involuntary hand movements can not within the very short time period during which a single line is traversed move the handpiece back to the line previously traversed which would lead to uneven treatment of the target surface.
If an interlacing traversing pattern were utilized, i.e. every second line of the target surface area is traversed and after that the remaining lines inbetween are traversed, there would be sufficient time between traversing of neighbouring lines to allow involuntary movements of the handpiece to a line previously traversed leading to repeated treatment of one area that may damage tissue at that area and leaving another area without treatment.
Thus, according to a third aspect of the invention, a method is provided of traversing a light beam across an area of a tissue, comprising the steps of emitting the light beam towards the tissue area, deflecting the light beam with movable deflecting means so that the tissue is traversed by the light beam line by line sequentially, each line being traversed in the same direction.
The first deflecting control means may be adapted to control the first moving means so that the lines are traversed in the same direction whereby substantially the same amount of power per area is delivered uniformly across the target surface area leading to substantially the same temperature increase at any point of the target surface area after traversing.
When a target area is traversed line by line, it is preferred that movement of one mirror causes the light beam to traverse a line while movement of the other mirror moves the light beam to the next line. In the example above, the galvanometer preferably generates the line traversing as the galvanometer can move the mirror at a high speed, and the linear motor preferably generates the displacement of the light beam to the next line to be traversed.
As mentioned earlier, it is preferred to control the amount of energy delivered to cells to be ablated, as the amount of energy must be sufficient for the dermnal cells to vaporize and, simultaneously, the amount of residual energy heating non-ablated cells must be so low that non-ablated cells will not be seriously damaged. Thus, when an area of tissue is traversed, e.g. line by line, it is preferred that neighbouring lines substantially abut each other. Clinical investigations have shown that, typically, an overlap of 0.1 to 0.2 mm is acceptable, and a distance between traversed lines of up to 0.1-0.2 mm is acceptable.
In order to control positioning of curves on the target area this accurately, it is preferred to position the movable deflecting means extremely accurately in the handpiece. In the preferred embodiment of the invention, this is accomplished by utilisation of printed circuit technology providing high accuracies of hole positioning of 0.05 mm. The mirrors are rotated around shafts that are mounted in printed circuit boards providing the required positioning accuracy. Further, the motors rotating the mirrors are also mounted on the printed circuit boards providing electrical connections to the motors and the mechanical support and positioning needed.
When traversing a target surface area line by line, it is preferred to traverse each line in the same direction ensuring uniform heating of cells across the target surface area. Further, it is preferred to provide light switching means for preventing emission of the light beam and light switching control means for controlling the light switching means for turning off the light beam, e.g. by switching off the light source, by inserting a light obstructing member in the light path of the beam, etc, while the light beam is moved from the end of a line having been traversed to the start of the next line to be traversed, in order to avoid repeated illumination of areas of the two lines.
Instead of turning the light source off, the light beam may be moved at a speed significantly larger than the traversing speed, during movement from the end of a line to the start of the next line.
Typically, the intensity within the beam of a light beam as generated by the light source varies as a normal function of the distance from the centre of the beam. The optical fiber may be designed or selected to be dispersive in such a way that the intensity function of the light beam emitted from the fiber as a function of the distance to the centre of the beam is substantially rectangular, i.e. the intensity of the beam leaving the fiber decays more slowly towards the edge of the beam than the intensity of a beam as generated by the light source whereby heat is more uniformly generated in cells across a traversed line of tissue.
By pulse width modulating the light source, energy delivered to the target surface may be varied along a traversed line. A fade-in area may be created by starting traversing of each traversed line with short pulses of light between longer periods of no light. As the line is traversed, the duration of the light pulses may be increased while the periods with no light may be decreased. Outside the fade-in area, the light beam may not be pulsed whereby the remaining part of each line is traversed with a constant intensity of the light beam.
Likewise, a fade-out area may be created by after having traversed a part of a line with constant light intensity, pulse width modulating the light source to transmit shorter and shorter pulses of light towards the line at the target surface area ending with no light transmitted at the end of the line.
The fade-in or fade-out traversing patterns may also be created by gradually increasing or decreasing, respectively, the power of the light source, or by decreasing or increasing, respectively, the traversing speed of the light beam.
Alternatively, a combination of these methods may be used.
The shape of the traversed area including the fading area may for example be polygonal, such as rectangular, quadratic, triangular, etc, circular, elliptic, etc.
A traversed line with fade-in and/or fade-out provides a smooth transition from a non-ablated area of tissue to an ablated area of tissue. This is a particularly advantageous feature when the handpiece according to the present invention is used for treatment of small marks on the tissue such as marks from chloasma, liver spots, red spots, tattoos, blood vessels etc.
Light intensity control means may be provided for generating a control signal for transmission to a light source interconnected with the optical fiber and controlling intensity of light emitted by the light source and transmitted through the optical fiber.
The fade-in and fade-out may be provided by controlling the intensity of the light beam and/or the velocity of the traversing light beam along a desired curve and the light intensity control means and/or the deflecting control means may be adapted to provide fade-in and fade-out.
The light intensity control means and/or the deflecting control means may be adapted to control the intensity of the light beam and/or the velocity of the traversing light beam along a desired curve as a function of the position of the light beam inside the area of the target surface area.
To provide the normal ablating of tissue, the light intensity control means may be adapted to provide a substantially constant intensity of the light beam and the deflecting control means may be adapted to provide a substantially constant velocity of the traversing light beam when the traversing light beam is inside a first part of the target surface area.
Keeping the intensity of the light beam substantially at the constant level as provided inside the first part of the target tissue, fade-in and fade-out may be provided by traversing the light beam with a velocity larger than the substantially constant traversing velocity within the first part of the target tissue area.
Likewise, keeping the velocity of the traversing light beam substantially constant inside the first part of the target tissue, the fade-in and fade-out may be provided by emitting a light beam with a smaller intensity than the substantially constant intensity of light emitted within the first part of the target tissue area.
The light intensity control means and/or the deflecting control means may be adapted to provide a varying intensity of the light beam outside the first part of the target surface area. The intensity of the light beam may be varied between a first intensity being substantially identical to the substantially constant intensity in the first part of the target tissue area and zero intensity, i.e. no light is emitted from the output of the handpiece.
The user interface means may also enable selection of parameters relating to fade-in and fade-out, such as traversing velocity of the output light beam from the handpiece in the fade-in or the fade-out area, intensity of the output light beam emitted form the handpiece in the fade-in or the fade-out area, size of fade-in or fade-out areas, shape of fade-in or fade-out areas, etc.
The handpiece according to the present invention may comprise means for controlling the energy-per-area of the light beam along a desired curve on a target tissue area to be resurfaced. In order to obtain the best results when ablating tissue, the energy-per-area of the light beam inside the first part of the target tissue area, should be kept at a substantially constant level.
In order to provide fade-in or fade-out, the energy-per-area of the light beam when outside the first part of the target tissue area may depend on the distance to the first part of the target tissue area, and it is preferred that the energy-per-area of the light beam increases with decreasing distance to the first part of the target tissue area.
In the case where the light beam is invisible, i.e. the wavelength of the light beam is e.g. in the infra red or ultra violet range, a light source generating visible light may be provided for generating a visible light beam that is used to assist the operator by indicating areas towards which the invisible light is directed during traversing. For example, the input connector of the handpiece may be further adapted to connect a second beam-outlet end of a second optical fiber for transmission of a visible light beam to the handpiece. The second optical fiber is aligned in the connector along the desired path of the visible light beam. The handpiece may further comprise movable second deflecting means for deflection of the visible light beam in such a way that the invisible light beam and the visible light beams emitted from the output of the handpiece illuminate substantially the same area of a target surface.
Further, two crossing visible light beams may be emitted from the handpiece, the cross point of the beams indicating the focus point of the invisible light beam.
Preferably, common moving deflecting means are utilised for deflection of all light beams emitted from the handpiece. Zinc selenide lenses may be utilized, as they are transparent for visible light as well as for infra-red light.
In order to further assist the operator of the apparatus, the visible light beam may, e.g. between traversing with the invisible light beam, be traversed around at least a part of the circumference of the target surface area thereby indicating the size, shape and position of the target surface area to be traversed with the invisible light beam.
When a polygonal shape of the target surface area has been selected, the visible light beam may, e.g. between traversing by the invisible light beam, be traversed along one edge of the polygon.
Thus, the method may further comprise the step of transmitting a visible light beam towards the target surface area utilizing the movable deflecting means.
The method may further comprise the step of traversing the visible light beam along at least a part of the circumference of the target surface area to be traversed by the invisible light beam.
When the shape of the tissue area traversed is polygonal, the method may comprise traversing the visible light beam along one edge of the polygon to be traversed by the invisible light beam.
In order to assist the operator of the apparatus in keeping a constant distance from the output of the handpiece to the surface of the tissue to be ablated, the handpiece may comprise a distance member connected to the handpiece at the output with fastening means.
As the distance member will touch the patient, it is desirable to insert a new, disinfected member before treatment of a new patient and thus, it is preferred that the fastening means comprises a magnet so that a used distance member can easily be disconnected from the handpiece, e.g. for autoclaving, and so that a new member can easily be connected to the handpiece.
The handpiece according to the present invention may further comprise a processor for control of the handpiece and comprising one or more control means, such as deflecting control means, light switching control means, means for controlling the light intensity control means, etc. The processor may further be connected to the user interface means and may be adapted to control the functions of the handpiece in accordance with the user interface selections.
Thus, the processor may be adapted to control energy density received by the target surface when traversed by the invisible light beam.
Further, the processor may be adapted to control energy density received by the target surface at a specific position as a function of the position along a desired curve traversed by the invisible light beam e.g. in order to provide fade-in and fade-out.
The processor may comprise a memory, such as an EEPROM, for storing of different parameters of traversing patterns and fade-in and fade-out patterns, such as target surface area size, traversing duration, etc.
The handpiece may further be provided with a computer interface facilitating reception of traversing pattern parameters generated in a computer and transmitted to the handpiece for storage in the memory. The user interface may utilized for selection of a specific traversing pattern from the set of patterns stored in the memory as previously described. The computer may be any programmable electronic device capable of storing, retrieving and processing data, such as a PC.
It is an important advantage of provision of a processor in the handpiece that signal lines between the handpiece and an external device controlling the handpiece are not needed. This reduces weight of the handpiece with cables connected. Further, electrical noise on control lines is minimized because of reduced lengths of the lines. Still further, control speed is increased as capacitance of a short line is small.
Various traversing patterns may be created on a PC and be downloaded to the memory of the handpiece. The patterns may stored in the form of a table of parameters defining number of lines, length of lines, distance between lines, start and end points of fade-in and fade-out of each line, points of turn on and turn off of the traversing light beam, etc of each traversing pattern stored.
A traversing pattern box may be provided, containing a processor, a memory and interface means for storage of traversing patterns generated, e.g. on a PC and transmitted to the box through the interface means for storage in the memory. The interface means of the box and the computer interface of a handpiece may be interconnected and the various traversing patterns stored in the box may be transferred to the memory of the handpiece whereby traversing patterns created at a single PC may be distributed to a plurality of handpieces that may be situated remotely from the PC.
According to a fourth aspect of the invention, a cable i is provided, comprising an optical fiber for transmission of light through the fiber and positioned at the centre of the cable, a teflon tube for protection of the fiber against influence from the environment, the fiber being positioned within the teflon tube, a plastic tube for protection of the teflon tube and the fiber against mechanical stress, the teflon tube being positioned within the plastic tube, a wire for protection of the cable against tensions and overloads that is positioned next to the plastic tube, and a spiral tube for holding the optical fiber, the teflon tube, the plastic tube and the wire none of which are fixed in position relative to each other in the spiral tube but are allowed to move in relation to each other when the cable is bended whereby a very flexible cable is provided.
The cable may further comprise a second optical fiber positioned within the spiral tube next to the teflon tube for transmission of visible light.